OBJECTIVE QUESTIONS FOR NEET AIIMS JIPMER www wisedane
OBJECTIVE QUESTIONS FOR NEET AIIMS JIPMER www. wisedane. com
PHYSICS ELASTICITY AND FLUID MECHANICS MCQ’S SET 1 www. wisedane. com
Q 1. The following four wires of length L and radius r are made of the same material. Which of these will have the largest extension when the same tension is applied ? A. L = 50 cm; r = 0. 25 mm B. L = 100 cm, r = 0. 5 mm C. L = 200 cm, r = 1 mm D. L = 300 cm, r = 1. 5 mm www. wisedane. com
ANSWER (A) EXPLANATION Ø Here, L/r 2 is maximum when L = 50 cm and r = 0. 25 mm as compared to other cases. www. wisedane. com
Q 2. The graph shown was obtained from the experimental measurements of the period of the oscillation T for different masses M placed in the scale pan on the lower end of the spring balance. The most likely reason for the line not passing through the origin is that A. Spring did not obey Hooke’s law B. amplitude of oscillation was too large C. clock used needed regulation D. mass of the pan was not neglected www. wisedane. com
ANSWER (D) EXPLANATION Ø When no weight is placed in pan, and T 2 shows some value, it means, the pan is not weightless and hence the mass of the pan can not be neglected. www. wisedane. com
Q 3. One end of a uniform rod of mass m 1, uniform area of crosssection A is suspended from the roof and a mass m 2 is suspended from the other end. What is the stress at the mid point of the rod ? www. wisedane. com
ANSWER (C) EXPLANATION www. wisedane. com
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ANSWER (A) EXPLANATION www. wisedane. com
Q 5. Two wires of equal length and cross –section area suspended as shown in Figure. Their Young’s modulus are Y 1 and Y 2 respectively. The equivalent Young’s modulus will be : www. wisedane. com
ANSWER (B) EXPLANATION www. wisedane. com
Q 6. IF the ratio of lengths, radii and Young’s modulii of steel and brass wires in the figure a, b, c respectively. Then the corresponding ratio of increase in their length would be : www. wisedane. com
ANSWER (B) EXPLANATION www. wisedane. com
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ANSWER (C) EXPLANATION www. wisedane. com
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ANSWER (C) EXPLANATION Ø When wire goes over a pulley and weight W is attached each free end of wire, then the tension in the wire is doubled, but the original length of wire is reduced to half, so extension in the wire is www. wisedane. com
Q 9. A stress of 1 kg/mm 2 is applied on a wire. If the modulus of elasticity of the wire is 1010 dyne/cm 2, then the percentage increase in the length of the wire will be : A. 0. 0098 % B. 0. 98 % C. 9. 8 % D. 98% www. wisedane. com
ANSWER (B) EXPLAINATION www. wisedane. com
Q 10. A spherical ball contracts in volume by 0. 01 % when subjected to a normal uniform pressure of 100 atmosphere. The bulk modulus of its material in dynes/cm 2 is : www. wisedane. com
ANSWER (C) EXPLANATION www. wisedane. com
A. 45 m B. 90 cm C. 135 m D. 180 cm www. wisedane. com
ANSWER (B) EXPLANATION www. wisedane. com
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ANSWER (C) EXPLANATION www. wisedane. com
Q 13. The upper end of a wire 1 metre long and 2 mm radius is clamped. The lower end is twisted through an angle of 45 o. The angle of the shear is : A. 0. 09 o B. 0. 9 o C. 9 o D. 90 o www. wisedane. com
ANSWER (A) EXPLANATION www. wisedane. com
Q 14. The two rods of the same material, whose radii are in the ratio 1 : 3 are twisted by applying equal torque on them. The ratio of twists produced in the rods will be : A. 81 : 1 B. 27 : 1 C. 18 : 1 D. 9 : 1 www. wisedane. com
ANSWER (A) EXPLANATION www. wisedane. com
Q 15. Two wires of equal lengths are made of same material suspended from a rigid support through one ends. Wire A has a diameter that is twice as that of wire B. If identical weights are suspended from the free ends of these wires, the increase in length is : A. Four times for wire A as for wire B B. Twice for wire A as for wire B C. Half for wire A as for wire B D. One fourth for wire A as for wire B www. wisedane. com
ANSWER (D) EXPLANATION www. wisedane. com
Q 16. 1 m 3 water is brought inside the lake upto 200 m detpth from the surface of the lake. What will be the change in the volume ? When the bilk modulus of elasticity of water is 22000 atmosphere, atmospheric pressure = 105 N/m 2 and g = 10 m/s 2. www. wisedane. com
ANSWER (A) EXPLANATION www. wisedane. com
A. 0. 08 J B. 0. 8 J C. 80 J D. 800 J www. wisedane. com
ANSWER (B) EXPLANATION www. wisedane. com
Q 18. A wire of length L and cross-section A is made of material of Young’s modulus Y. it is stretched by an amount x, the workdone is : www. wisedane. com
ANSWER (C) EXPLANATION www. wisedane. com
Q 19. A wire can be broken by applying a load of 20 kg wt. The force required to break the wire of twice the diameter (same length and same material ) is : A. 5 kg wt. B. 160 kg wt. C. 80 kg wt. D. 20 kg wt. www. wisedane. com
ANSWER (C) EXPLANATION www. wisedane. com
A. 66. 6 m B. 60. 0 m C. 33. 3 m D. 30. 0 m www. wisedane. com
ANSWER (C) EXPLANATION www. wisedane. com
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